More specifically, the machine according to this invention falls within the sector of processing containers (bottling, labelling, capping, . . . ). These containers may consist of bottles, cans or other containers not expressly indicated.
Usually, a machine for moving containers comprises an infeed conveyor belt for feeding the containers to an infeed station, an infeed transfer starwheel positioned at the infeed station for picking up one container at a time and carrying it to a loading station, and a rotary carrousel at the outer periphery of which there are stations for processing the containers. An example of this structure is described in patent application EP2382146 in the name of the same applicant as this invention.
In detail, the carousel comprises a plurality of rotatable plates, located along the relative periphery, and on which are positioned the containers (a container for each plate) once unloaded from the transfer starwheel.
As already mentioned, in effect, in the container processing field, the containers are loaded on a rotary carousel to which are associated various processing stations, which operate on the containers. These processing stations may be, for example, stations for applying labels, or filling stations, or stations for closing the bottles or the like.
According to first solution of the prior art, a plurality of sensors are mounted on the carousel, each located at a plate. More specifically, again according to the prior art, each sensor detects, during rotation of the container on the relative plate, a distinctive mark on the bottle (commonly know as “spot”) which may be, if, for example, it is a glass bottle, the glass seam, a logo prepared on the glass (on which, for example, a label is to be applied), or yet other marks.
Once the sensor has detected the bottle “spot”, a control unit connected to the sensor processes the signal and associates it with the corner in which the plate is positioned at that precise moment. In this way the initial orientation of the bottle on the plate is known.
The knowledge of the initial orientation of the container is important because, in that way, it is possible to rotate the plate by a predetermined angle in such a way as to bring a predetermined part of the lateral surface of the bottle on which, for example, to apply a label at the labelling station. Normally, each sensor is connected to the carousel (at a plate) using a bracket and it rotates integrally with the carousel so as to follow each container during rotation of the carousel.
Each bracket is normally connected to an upper part of the carousel and it extends mainly in a vertical direction towards the plates. In other words, the carousel normally has a plurality of vertical rods distributed along the perimeter of the carousel.
However, this first prior art technique has several disadvantage.
More specifically, a first disadvantage is linked to the fact that the presence of a plurality of rods and a plurality of sensors further complicates the structure of the carousel and increases the dimensions of the carousel.
In addition, the presence of a plurality of brackets distributed around the carousel hinders access to the internal components of the carousel, such as when, for example, it is necessary to carry out the maintenance or replacement of components.
Moreover, a further disadvantage is linked to the fact that it is necessary to have as many sensors as there are plates of the carousel. Therefore, in the case of large carousels with many stations, it is necessary to have a large number of detection sensors. Consequently, the presence of many sensors increases the final cost of the carousel due both to the costs of the sensors themselves and the costs of the structures which support them.
In a second prior art technique described in patent documents EP2658783 and DE1805010 the carousel comprises a single sensor movable along the outer perimeter of the carousel over a predetermined arc to detect the orientation of each container and then return to the starting position in order to detect the orientation of the new container and so on . . . . The sensor is connected to the carousel through an arm which protrudes outside of it up to the height of the container.
However, this second known technology has certain disadvantages.
More specifically, in this case it is necessary to wait for the container to carry out a complete rotation about itself in such a way as to detect the spot for identifying the respective orientation. During the rotation of the container (and therefore of the plate) the carousel rotates and therefore a part of the angle of rotation of the carousel is lost for detecting the orientation of the container. Consequently, it is necessary to dimension the radius of the carousel both as a function of the number of work stations to be connected to it, and as a function of the space necessary for the initial detection of the orientation of the container.
In addition, a dedicated structure is necessary for moving the arm which supports the sensor along the predetermined angle. This movement of the arm must also be synchronised with the movement of the carousel in such a way that the sensor can follow a corresponding container.
Lastly, since above each plate there is a cap-pressing head to hold the container stationary in position, the known detection systems do not allow a “spot” located on the cap of a bottle or on the top surface of the container to be detected since it is masked by the cap-pressing head.
In a third prior art technique illustrated in patent document WO/03024808 there is a detector positioned upstream of the carousel and configured for detecting a text present on the cap of the container before the latter is transferred on the carrousel. Following the transfer of the container into the carousel, the plate is rotated by a predetermined angle already calculated as a function the position of the text detected on the cap in order to apply the label.
However, this prior art technique has several of disadvantages due to the fact that the text present on the cap is never correlated with the area of the lateral surface on which the label is to be applied. For this reason, it is not possible to have control over the position for application of the label. In addition, by using this prior art technique it is possible to operate only with containers which have a cap (sometimes the capping step occurs subsequently) and having a text (not all the caps have a text). In this situation, the aim of this invention is to provide a machine for moving containers which overcomes the above-mentioned disadvantages.